Poly-(pyrrole-3-carboxylic acid) Based Nanostructured Platform for the Detection of Carcinoembryonic Antigen

A nanostructured platform based on pyrrole 3-carboxylic acid was developed and it was used for the detection of carcinoembryonic antigen, a biomarker for gastro-intestinal tract cancers. The conductive polymer offers possibilities for functionalization due to the presence of the carboxylic group. The platform was tailored by polymerizing pyrrole 3-carboxylic acid at the surface of a graphite-based screen-printed electrode by using multiple pulse amperometry and cyclic voltammetry. The carboxylic groups were activated, facilitating the formation of amide covalent bonds with the terminal amine groups from the antibody. Each step's optimization was tracked by performing electrochemical impedance spectroscopy. The immunosensor was successfully applied for the detection of carcinoembryonic antigen in synthetic samples. By comparing pyrrole 3-carboxylic acid with pyrrole, significantly greater increases of the charge transfer resistance were achieved by using the functionalized monomer for the immobilization step. The binding of the anti-CEA was reproducible and directly proportional with its concentration. The increase of the charge transfer resistance after the incubation with carcinoembryonic antigen was linearly correlated with the concentration of the sample and the LOD was 33.33pgmL(-1). A simple nanostructured platform for the label-free detection of a carcinogenic biomarker molecule was developed, thus holding great opportunities for clinical diagnostics and other biosensor applications.